Mold stack for a preform

ABSTRACT

According to embodiments of the present invention, there is provided a stripper assembly and a mold stack incorporating same. More specifically, there is provided the stripper assembly ( 212 ) for use in a mold stack ( 202 ) for forming a preform ( 210 ) suitable for blow-molding into a final-shaped container. The stripper assembly ( 212 ) comprises a stripper plate ( 214 ) connectable, in use, to a stripper plate actuator; neck rings ( 220 ) configured to cooperate to define a portion a neck region ( 226 ) of the preform ( 210 ); a stripper ring ( 230 ) configured to define at least a portion of a top sealing surface of the neck region ( 226 ) of the preform ( 210 ); the stripper plate ( 214 ) being configured to actuate the neck rings ( 220 ) and the stripper ring ( 230 ), in unison, along substantially the whole length of a complete ejection path, which is substantially parallel to a longitudinal axis of the mold stack ( 202 ); and wherein the neck rings ( 220 ) are configured for movement in a direction substantially perpendicular to the longitudinal axis of the mold stack, over at a portion of the complete ejection path, whereby at a completion of the complete ejection path, the stripper ring ( 230 ) and the neck rings ( 220 ) render the preform ( 210 ) removable from the mold stack ( 202 ).

TECHNICAL FIELD

The present invention generally relates to, but is not limited to, amolding system, and more specifically the present invention relates to,but is not limited to, a mold stack for a preform.

BACKGROUND OF THE INVENTION

Molding is a process by virtue of which a molded article can be formedfrom molding material by using a molding system. Various molded articlescan be formed by using the molding process, such as an injection moldingprocess. One example of a molded article that can be formed, forexample, from polyethylene terephthalate (PET) material is a preformthat is capable of being subsequently blown into a beverage container,such as, a bottle and the like.

As an illustration, injection molding of PET material involves heatingthe PET material (or other suitable molding material for that matter) toa homogeneous molten state and injecting, under pressure, the so-meltedPET material into a molding cavity defined, at least in part, by afemale cavity piece and a male core piece mounted respectively on acavity plate and a core plate of a mold. The cavity plate and the coreplate are urged together and are held together by clamp force, the clampforce being sufficient to keep the cavity and the core pieces togetheragainst the pressure of the injected PET material. The molding cavityhas a shape that substantially corresponds to a final cold-state shapeof the molded article to be molded. The so-injected PET material is thencooled to a temperature sufficient to enable ejection of the so-formedmolded article from the molding cavity. When cooled, the molded articleshrinks inside of the molding cavity and, as such, when the cavity andcore plates are urged apart, the molded article tends to remainassociated with the core piece. Accordingly, by urging the core plateaway from the cavity plate, the molded article can be subsequentlydemolded by ejecting it off the core piece. Ejection structures areknown to assist in removing the molded articles from the core halves.Examples of the ejection structures include stripper plates, stripperrings and neck rings, ejector pins, etc.

When dealing with molding a preform that is capable of beingsubsequently blown into a beverage container, one consideration thatneeds to be addressed is forming a so-called “neck region”. Typicallyand as an example, the neck region includes (i) threads (or othersuitable structure) for accepting and retaining a closure assembly (ex.a bottle cap), and (ii) an anti-pilferage assembly to cooperate, forexample, with the closure assembly to indicate whether the end product(i.e. the beverage container that has been filled with a beverage andshipped to a store) has been tampered with in any way. The neck regionmay comprise other additional elements used for various purposes, forexample, to cooperate with parts of the molding system (ex. a supportledge, etc.). As is appreciated in the art, the neck region can not beeasily formed by using the cavity and core halves. Traditionally, splitmold inserts (sometimes referred to by those skilled in the art as “neckrings”) have been used to form the neck region.

With reference to FIG. 1, a section along a portion of an injection mold50 illustrates a typical molding insert stack assembly 52 that can bearranged (in use) within a molding machine (not depicted). Thedescription of FIG. 1 that will be presented herein below will begreatly simplified, as it is expected that one skilled in the art willappreciate configuration of other components of the injection mold 50that will not be discussed in the following description.

The molding insert stack assembly 52 includes a split mold insert pair54 that together with a mold cavity insert 56, a gate insert 58 and acore insert 60 defines a molding cavity 62. Molding material can beinjected into the molding cavity 62 from a source of molding material(not depicted) via a receptacle (not separately numbered) in the gateinsert 58 to form a molded article. In order to facilitate forming ofthe neck region of the molded article and subsequent removal of themolded article therefrom, the split mold insert pair 54 comprises a pairof complementary split mold inserts (not separately numbered) that aremounted on adjacent slides of a slide pair (not depicted). The slidepair is slidably mounted on a top surface of a stripper plate (notdepicted). As commonly known, and as, for example, generally describedin U.S. Pat. No. 6,799,962 to Mai et al (granted on Oct. 5, 2004), thestripper plate (not depicted) is configured to be movable relative tothe cavity insert 56 and the core insert 60, when the mold is arrangedin an open configuration, whereby the slide pair, and the complementarysplit mold inserts mounted thereon, can be laterally driven, via a camarrangement (not shown) or any other suitable known means, for therelease of the molded article from the molding cavity 62.

Several types of the split mold insert pair 54 are known in the art. Forexample, the split mold insert pair 54 can be of a cavity-lock type or acore-lock type (depicted in FIG. 1), depending on an arrangement that isused for locking the split mold insert pair 54, in use, relative to themold cavity insert 56 and the core insert 60. The split mold insert pair54 can also define a portion of the neck region (as is the case inFIG. 1) or the whole of the neck region or, put another way,“encapsulate” the neck region. One of the functions performed by thesplit mold insert pair 54 is to assist in ejecting the molded articleoff the core insert 60 by “sliding” the molded article off the coreinsert 60.

An example of the latter is disclosed in a co-owned U.S. Pat. No.6,989,124 issued on Jan. 24, 2006 to Miller et al., which teaches aninjection molding method and apparatus for ejecting a molded plasticarticle from a mold. A lifting structure and/or step is provided with alifting portion which is configured to contact substantially one half ofan end of the molded plastic article along a line substantiallyperpendicular to the lifting direction. Since the molded plastic articleis lifted by its end, the article does not have to be solidified at itsinterior, thus allowing earlier removal of the article from the mold,reducing cycle time. A tapered surface forms an acute angle with respectto the lifting portion to form a tight seal with the mold, preventingleakage. Preferably, the neck ring engages only an outer circumferentialportion of the molded plastic article during a majority of a moldopening stroke.

Co-owned U.S. Pat. No. 7,128,865 issued to Martin on Oct. 31, 206discloses an injection molding method and apparatus for ejecting amolded plastic preform from a mold. A first lifting structure and/orstep is configured to have an inner surface with an area for sealing andaligning with a complementary surface on a core, and to have an uppersurface with an area for sealing and aligning with a complementarysurface on a second lifting structure, said upper surface of said firstlifting structure being configured to lift a molded plastic preform fromthe injection mold in a lifting direction for a first period of time,the lower portion of the molded plastic preform lying in a planesubstantially perpendicular to the lifting direction. A second liftingstructure and/or step is configured to have an inner surface configuredto lift an outer surface of the molded plastic preform from theinjection mold in the lifting direction for a second period of time, theouter surface of the molded plastic preform including structure lying ina plane substantially parallel with the lifting direction. Since themolded plastic preform is lifted by its end, the preform does not haveto be solidified at its interior, thus allowing earlier removal of thepreform from the mold, reducing cycle time.

SUMMARY OF THE INVENTION

According to a first broad aspect of the present invention, there isprovided a stripper assembly for use in a mold stack for forming apreform suitable for blow-molding into a final-shaped container. Thestripper assembly comprises a stripper plate connectable, in use, to astripper plate actuator; neck rings configured to cooperate to define aportion a neck region of the preform; a stripper ring configured todefine at least a portion of a top sealing surface of the neck region ofthe preform; the stripper plate being configured to actuate the neckrings and the stripper ring, in unison, along substantially the wholelength of a complete ejection path, which is substantially parallel to alongitudinal axis of the mold stack; and wherein the neck rings areconfigured for movement in a direction substantially perpendicular tothe longitudinal axis of the mold stack, over at a portion of thecomplete ejection path, whereby at a completion of the complete ejectionpath, the stripper ring and the neck rings render the preform removablefrom the mold stack.

According to a second broad aspect of the present invention, there isprovided a mold stack for forming a preform suitable for blow-moldinginto a final-shaped container. The mold stack comprises a core insertand a cavity insert cooperating to define a molding cavity to form aportion of the preform; a stripper assembly for removing the preformfrom the core insert, the stripper assembly comprising: a stripper plateconnectable, in use, to a stripper plate actuator; neck rings configuredto cooperate to define a portion a neck region of the preform; astripper ring configured to define at least a portion of a top sealingsurface of the neck region of the preform; the stripper plate beingconfigured to actuate the neck rings and the stripper ring, in unison,along substantially the whole length of a complete ejection path, whichis substantially parallel to a longitudinal axis of the mold stack; andwherein the neck rings are configured for movement in a directionsubstantially perpendicular to the longitudinal axis of the mold stack,over at a second portion of the complete ejection path, whereby at acompletion of the complete ejection path, the stripper ring and the neckrings render the preform removable from the mold stack.

These and other aspects and features of non-limiting embodiments of thepresent invention will now become apparent to those skilled in the artupon review of the following description of specific non-limitingembodiments of the invention in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the non-limiting embodiments of the presentinvention (including alternatives and/or variations thereof) may beobtained with reference to the detailed description of the non-limitingembodiments along with the following drawings, in which:

FIG. 1 is a cross-section view of a portion of an injection mold 50 thatincorporates a typical molding insert stack assembly 52, implemented inaccordance with known techniques.

FIG. 2 and FIG. 3 depict a mold stack 202, implemented in accordancewith a non-limiting embodiment of the present invention, the mold stack202 being depicted in a molding configuration.

FIG. 4 and FIG. 5 depict the mold stack 202 of FIG. 2 and FIG. 3, themold stack 202 being depicted in a partially extended configuration,where a stripper assembly 212 has traveled a portion of a completeejection path.

FIG. 6 and FIG. 7 depict the mold stack 202 of FIG. 2 and FIG. 3, themold stack 202 being depicted in an extended configuration, where thestripper assembly 212 has traveled the whole of the complete ejectionpath.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

With reference to FIG. 2 and FIG. 3, a non-limiting embodiment of a moldstack 202 will now be described in greater detail, in which FIG. 2depicts a cross section taken along a longitudinal axis thereof and FIG.3 depicts a perspective view of a first instance and a partially cut-outsecond instance thereof.

The mold stack 202 is receivable in use within a core plate 204, whichis implemented according to conventional designs and, as such, will notbe described in great detail herein. More specifically, coupled to thecore plate 204 is a core insert 206. Construction of the core insert 206can be implemented in accordance with known techniques and, as such,will not be described in great detail herein. Suffice it to say that thecore insert 206 can be coupled to the core plate 204 by means of asuitable coupler, such as a bolt 208 and the like. Function of the coreinsert 206 is also well-known in the art and includes inter alia thefunction of defining an inner portion of a preform 210, the preform 210being of a kind suitable for subsequent blow-molding into a final-shapedcontainer, such as a beverage container or the like. Even though notdepicted, the mold stack 202 further includes a cavity insert, whichcooperates with the core insert 206 to define portions of a moldingcavity that forms the preform 210. The cavity insert can be implementedin a substantially similar manner to the mold cavity insert 56 of FIG.1.

The mold stack 202 further includes a stripper assembly 212. Within theembodiment illustrated, the stripper assembly 212 includes a stripperplate 214, a wear plate 216, two instances of a neck ring slide 218(referred together as neck ring slides 218) and neck rings 220. Thestripper plate 214 is operatively coupled to a stripper plate actuator,which is not depicted, but is well-known to those of skill in the art(for example, a hydraulic actuator, a servo-motor actuator and thelike). The stripper plate actuator (not depicted) is configured to movethe stripper plate, back and forth, in a direction depicted in FIG. 2 at“L” or, in other words, a direction, which is substantially parallel tothe longitudinal axis of the mold stack 202.

Within the illustration, the neck rings 220 are of a cavity-lock type.The neck rings 220 perform at least two functions—defining a portion ofa neck region 226 of the preform 210 and assisting in ejection of thepreform 210 off the core insert 206. For the performance of the ejectionfunction, the neck rings 220 are operatively coupled to the neck ringslides 218 by suitable means, such as bolts 222 (shown in FIG. 3), formovement therewith as will be described momentarily. The neck ringslides 218 are coupled to a neck ring slide actuator (not depicted),which can be implemented as cam(s), servo motor(s) and the like. Theneck ring slide actuator (not depicted) is configured to move the neckring slides 218, back and forth, in a direction depicted in FIG. 3 at“S” or in other words a direction which is substantially perpendicularto a longitudinal axis of the mold stack 202. The wear plate 216 isprovided between the stripper plate 214 and the neck ring slides 218 toprevent substantial damage to the stripper plate 214 and/or neck ringslides 218 during the movement of the neck ring slides 218 relative tothe stripper plate 214 in the direction “S”. The wear plate 216 isimplemented according to known techniques and is coupled to the stripperplate 214 by suitable couplers, such as bolts 224 and the like.

So far, implementation of the stripper assembly 212 is substantiallysimilar to that of the prior art approaches. Accordingly, those skilledin the art will easily appreciate how the stripper assembly 212functions. However, for the benefit of the reader, a brief descriptionwill be presented. It is worthwhile noting that FIG. 2 and FIG. 3 depictthe mold stack 202 in a “molding configuration”. The moldingconfiguration is a configuration whereby a mold (not depicted) housingthe mold stack 202 and the aforementioned cavity insert (not depicted),as well as other stack components potentially present therein, is closed(and, potentially, clamped) and the preform 210 is being molded or, asis the case in FIGS. 2 and 3, the preform 210 has been molded and eitherundergoes or has undergone in-mold cooling.

When a mold (not depicted) housing the mold stack 202 is unclamped andstarts to open, the stripper plate actuator (not depicted) actuates thestripper plate 214 in a right-bound direction, as viewed in FIG. 2. Thewear plate 216, the neck ring slides 218 and the neck rings 220initially start to move, in unison, with the stripper plate 214,effectively moving the preform 210 in the right-bound direction, so thatit can be eventually removed from the core insert 206. After a certainportion of this movement (which is determined, amongst other things, bythe length of the preform 210, etc.), the neck ring slides actuator (notdepicted) starts to actuate the neck ring slides 218 (and, therefore,the neck rings 220) outwardly into the direction “S”. At this point, thewear plate 216, the neck ring slides 218 and the neck rings 220 continueto move in the direction “L”, while the neck ring slides 218 and theneck rings 220 also move in the direction “S”. Eventually, the twohalves of the neck rings 220 are separated enough to let the neck region226, which includes several undercuts such as a thread, ananti-tampering ledge, etc. (all of these undercuts not separatelynumbered), of the preform 210 to be removed from the mold stack 202.

Eventually, the preform 210 is removed from the core insert 206 and istransferred to a suitable downstream processing device (not depicted),such as a take-off robot (not depicted) and the like. It is worthwhilenoting that a path of travel traveled by the stripper assembly 212, inthe direction “L” (i.e. the longitudinal direction) between the positionshowed in FIG. 2 and a position where the preform 210 is removed fromthe core insert 206, can be thought of as a “complete ejection path” ofthe stripper assembly 212.

According to a non-limiting embodiment of the present invention, thestripper assembly 212 further comprises a stripper ring 230. Thestripper ring 230 is coupled to the stripper plate 214 for movementtherewith, back and forth, in the direction “L” (FIG. 2). Therefore, itis noted that both the stripper ring 230 and the neck ring slides 218(and, therefore, the neck rings 220) are actuated in the direction “L”by the same means, i.e. by means of the stripper plate 214 (and thestripper plate actuator, which is not depicted).

In the specific non-limiting embodiment of the present inventiondepicted in FIG. 2 and FIG. 3, the stripper ring 230 is coupled to thestripper plate 214 in the following manner. Defined between the stripperplate 214 and the wear plate 216 is a pocket 232. The stripper ring 230,on the other hand, comprises an annular step 234, which is complementaryin shape to the pocket 232. Recalling that the wear plate 216 is coupledto the stripper plate 214 by means of bolts 224, when assembled, theannular step 234 gets trapped within the pocket 232. Within the specificembodiment depicted herein, the specific coupling arrangement affords acertain degree of float to the stripper ring 230, which may compensatefor any ads-alignment potentially present between components of the moldstack 202. Therefore, it can be said that within this embodiment of thepresent invention, the stripper ring 230 is coupled to the stripperplate 214 in a floatable arrangement. However, in alternativenon-limiting embodiments of the present invention, the coupling betweenthe stripper ring 230 and the stripper plate 214 can be executed bydifferent means, such as by means of bolts or other suitable couplers(which may, but do not have to, afford the same or different degree offloat to the stripper ring 230).

The stripper ring 230 includes a molding cavity defining portion 235,which in use defines a portion of the preform 210 or, more specifically,a top portion of the neck region 226, also known in the art as “TSS” or“Top Sealing Surface”.

Within the context of operation of the stripper assembly 212 presentedabove, operation of the stripper ring 230 will be explained in greaterdetail with reference to FIG. 2 and FIG. 3 (depicting a moldingconfiguration thereof), FIG. 4 and FIG. 5 (depicting a configurationwhere the mold stack 202 is in a partially extended configuration, wherethe stripper assembly 212 has traveled a portion of the completeejection path) and FIG. 6 and FIG. 7 (depicting a configuration wherethe mold stack 202 is in a fully extended configuration, where thestripper assembly 212 has traveled the whole of the complete ejectionpath). It is worthwhile noting that some of the numerals shown in FIG. 2and FIG. 3 have been omitted, for the sake of simplicity, from FIG. 4,FIG. 5, FIG. 6 and FIG. 7.

For the purposes of the description to be presented herein below, itshall be assumed that within the illustration of FIG. 2 and FIG. 3, themold stack 202 is shown in the molding configuration where the preform210 has been molded and has undergone in-mold cooling. At this point,the mold (not depicted) housing the mold stack 202 is unclamped andstarts to open and the stripper plate actuator (not depicted) actuatesthe stripper plate 214 in a right-bound direction, as viewed in FIG. 2.The wear plate 216, the neck ring slides 218, the neck rings 220 and thestripper ring 230 initially start to move, in unison, with the stripperplate 214, effectively moving the preform 210 in the right-bounddirection along a portion of the complete ejection path (i.e. in thedirection “L”). This portion of the complete ejection path, where theneck rings 220 and the stripper ring 230 are moving in unison can beconsidered to be “a first portion” of the complete ejection path.

With reference to FIG. 4 and FIG. 5, after a certain portion of thismovement (which is determined, amongst other things, by the length ofthe preform 210, etc.), the neck ring slides actuator (not depicted)starts to actuate the neck ring slides 218 (and, therefore, the neckrings 220) outwardly into the direction “S” (FIG. 5). This portion ofthe complete ejection path can be considered to be a beginning of a“second portion” of the complete ejection path, where the wear plate216, the neck ring slides 218, the neck rings 220 and the stripper ring230 continue the movement in the right-bound portion of the direction“L”, while the neck ring slides 218 and the neck rings 220 continue themovement in the outbound portion of the direction “S”.

FIG. 6 and FIG. 7 depict the mold stack 202 in a position where the moldstack 202 has completed the whole of the complete ejection path. At thispoint, the wear plate 216, the neck ring slides 218, the neck rings 220and the stripper ring 230 have completed the movement in the right-boundportion of the direction “L” (FIG. 6), while the neck ring slides 218and the neck rings 220 also have completed the movement in the outboundportion of the direction “S” (FIG. 7). As a result of this, the twohalves of the neck rings 220 have been separated enough to allow theneck region 226 of the preform 210 to be removed from the mold stack202. In other words, at a completion of the complete ejection path, thepreform 210 is rendered removable from the mold stack 202.

This sequence of actuation of the neck rings 220 and the stripper ring230 results in a technical effect of embodiments of the presentinvention whereby both the stripper ring 230 and the neck rings 220assist in ejection of the preform 210 off the core insert 206. Morespecifically, during the first portion of the complete ejection path,both the stripper ring 230 and the neck rings 220 assist in moving thepreform 210 off the core insert 206. During the second portion of thecomplete ejection path, the stripper ring 230 continues to move thepreform 210 off the core insert 206, while halves of the neck rings 220are separated to render the preform 210 demoldable. For the avoidance ofdoubt, is should be understood that the neck rings 220 are actuated inthe direction “S” only during a portion of the complete ejection path,i.e. during the aforementioned second portion thereof.

It is noted that within this illustration, the neck ring slides 218 andthe stripper ring 230 are both actuated by the same actuator (i.e. thestripper plate 214 and the stripper plate actuator, which is notdepicted) and they have also traveled together in the longitudinaldirection (i.e. direction “L”) for substantially the whole length of thecomplete ejection path. It is also worthwhile noting and recalling thatthe stripper ring 230 defines a portion of the preform 210 (and morespecifically a portion of the top sealing surface), the stripper ring203 effectively “pushes” the preform 210 off the core insert 206 duringthe movement along the complete ejection path.

A technical effect of embodiments of the present invention includes atleast partial mitigation of certain demolding defects, attributable atleast partially to the pushing exerted by the stripper ring 230 onto thetop portion of the preform 210 (and, more specifically, onto a portionof the Top Sealing Surface of the preform 210). Another technical effectof embodiments of the present invention includes simplicity of assembly,which is attributable at least partially to the fact that the neck ringslides 218 and the stripper ring 230 are actuated by a single actuator(i.e. the stripper plate 214 and the stripper plate actuator, which isnot depicted).

It is noted that embodiments described herein above are meant asexamples only. Constructions of certain components of the mold stack 202can be varied and certain other components can be omitted altogether.For example, in certain embodiments of the present invention, the wearplate 216 can be omitted from the mold stack 202.

Description of the non-limiting embodiments of the present inventionsprovides examples of the present invention, and these examples do notlimit the scope of the present invention. It is to be expresslyunderstood that the scope of the present invention is limited by theclaims. The concepts described above may be adapted for specificconditions and/or functions, and may be further extended to a variety ofother applications that are within the scope of the present invention.Having thus described the non-limiting embodiments of the presentinvention, it will be apparent that modifications and enhancements arepossible without departing from the concepts as described. Therefore,what is to be protected by way of letters patent are limited only by thescope of the following claims:

1. A stripper assembly (212) for use in a mold stack (202) for forming apreform (210) suitable for blow-molding into a final-shaped container,the stripper assembly (212) comprising: a stripper plate (214)connectable, in use, to a stripper plate actuator; neck rings (220)configured to cooperate to define a portion a neck region (226) of thepreform (210); a stripper ring (230) configured to define at least aportion of a top sealing surface of the neck region (226) of the preform(210); the stripper plate (214) being configured to actuate the neckrings (220) and the stripper ring (230), in unison, along substantiallythe whole length of a complete ejection path, which is substantiallyparallel to a longitudinal axis of the mold stack (202); and wherein theneck rings (220) are configured for movement in a directionsubstantially perpendicular to the longitudinal axis of the mold stack,over at a portion of the complete ejection path, whereby at a completionof the complete ejection path, the stripper ring (230) and the neckrings (220) render the preform (210) removable from the mold stack(202).
 2. The stripper assembly (212) of claim 1, wherein the stripperring (230) is coupled to the stripper plate (214) in a floatablearrangement.
 3. The stripper assembly (212) of claim 2, wherein the neckrings (220) are coupled to a neck ring slide (218); and wherein thestripper assembly (212) further comprises a wear plate (216) disposedbetween the stripper plate (214) and the neck ring slide (218); andwherein, in use the stripper plate (214) and the wear plate (216) definea pocket (232); and wherein the stripper ring (230) comprises an annularstep (234) complementary in shape to the pocket (232); and wherein, inuse the stripper plate (214) and the wear plate (216) trap the annularstep (234) within the pocket (232).
 4. The stripper assembly (212) ofclaim 1, wherein the stripper plate (214) is coupled, in use, to thestripper plate actuator which is configured to actuate the stripperplate (214) along the longitudinal axis of the mold stack (202).
 5. Thestripper assembly (212) of claim 1, wherein the neck rings (220) arecoupled to a neck ring slide (218); and wherein the neck ring slide(218) is coupled, in use, to a neck ring slide actuator and wherein theneck ring slide actuator is configured to actuate the neck ring slide(218) in a direction substantially perpendicular to the longitudinalaxis of the mold stack (202).
 6. A mold stack (202) for forming apreform (210) suitable for blow-molding into a final-shaped container,the mold stack (202) comprising: a core insert (206) and a cavity insertcooperating to define a molding cavity to form a portion of the preform(210); a stripper assembly (212) for removing the preform (210) from thecore insert (206), the stripper assembly (212) comprising: a stripperplate (214) connectable, in use, to a stripper plate actuator; neckrings (220) configured to cooperate to define a portion a neck region(226) of the preform (210); a stripper ring (230) configured to defineat least a portion of a top sealing surface of the neck region (226) ofthe preform (210); the stripper plate (214) being configured to actuatethe neck rings (220) and the stripper ring (230), in unison, alongsubstantially the whole length of a complete ejection path, which issubstantially parallel to a longitudinal axis of the mold stack (202);and wherein the neck rings (220) are configured for movement in adirection substantially perpendicular to the longitudinal axis of themold stack, over at a second portion of the complete ejection path,whereby at a completion of the complete ejection path, the stripper ring(230) and the neck rings (220) render the preform (210) removable fromthe mold stack (202).
 7. The mold stack (202) of claim 6, wherein thestripper ring (230) is coupled to the stripper plate (214) in afloatable arrangement.
 8. The mold stack (202) of claim 7, wherein theneck rings (220) are coupled to a neck ring slide (218); and wherein thestripper assembly (212) further comprises a wear plate (216) disposedbetween the stripper plate (214) and the neck ring slide (218); andwherein, in use the stripper plate (214) and the wear plate (216) definea pocket (232); and wherein the stripper ring (230) comprises an annularstep (234) complementary in shape to the pocket (232); and wherein, inuse the stripper plate (214) and the wear plate (216) trap the annularstep (234) within the pocket (232).
 9. The mold stack (202) of claim 6,wherein the stripper plate (214) is coupled, in use, to the stripperplate actuator which is configured to actuate the stripper plate (214)along the longitudinal axis of the mold stack (202).
 10. The mold stack(202) of claim 6, wherein the neck rings (220) are coupled to a neckring slide (218); and wherein the neck ring slide (218) is coupled, inuse, to a neck ring slide actuator and wherein the neck ring slideactuator is configured to actuate the neck ring slide (218) in adirection substantially perpendicular to the longitudinal axis of themold stack (202).